JP3281750B2 - Cylindrical heater and fixing heat roller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat roller for fixing toner in an electrophotographic apparatus such as a printer, and a cylindrical heater used as a heater for hot water or a heater for heating.

[0002]

2. Description of the Related Art Conventionally, a toner fixing device in an electrophotographic apparatus such as a printer has a heat roller provided with a heat generating means and a pressure roller arranged opposite to each other, and a printed paper passes between these rollers. By doing so, the toner is heated and fixed.

[0003] As the above-mentioned heat roller, a roller in which a heating element such as a halogen lamp is provided in a metal pipe such as aluminum or stainless steel has been used. However, since the heat generation efficiency is low, a warm-up time of one minute or more is required. In addition, there is a problem that power consumption is large.

Therefore, a heating resistor is provided on the outer periphery of the metal pipe via an insulating layer made of an organic resin such as polyimide.
Further, a heat roller having a structure in which a release layer is provided on the surface thereof has been proposed (JP-A-55-72390, JP-A-55-72390).
2-200380).

It has also been proposed to use a mixture of glass and a conductive material such as a metal as a heating resistor layer of the heat roller (see Japanese Patent Application Laid-Open No. 63-158852). This is because a conductive material such as a metal has good wettability with glass and is easy to conform to, so that a heating resistor layer having a uniform thickness can be formed.

Further, as a heater for hot water, there is a heater having a structure in which a ceramic heater is attached to an outer periphery of a stainless steel pipe to warm water flowing in the pipe, and the same structure is used as a heater for heating.

[0007]

However, conventional cylindrical heaters such as a heat roller for fixing and a heater for hot water do not have a self-controlling function. There was a risk of accidents such as firing.

Further, when the release layer is worn out and the heating resistor layer is exposed or a part of the heating resistor layer is deteriorated while the fixing heat roller is used for a long period of time, the heating resistor layer is partially removed. In this case, the resistance becomes high, causing abnormal heat generation or destruction of the heat generating resistor layer, and there is a danger of electric leakage or ignition.

[0009]

[0010]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a cylindrical heater or a fixing heat roller having a heating resistor layer provided on the surface of a metal pipe via an insulating layer, wherein the heating resistor layer is formed of Ag. , Ni, Au, Pd, Mo, Mn,
A mixture of a conductive agent composed of at least one of W, Re ₂ O ₃ , Mn ₂ O ₃ , and LaMnO ₃ , a component composed of at least one of Al, Pb, and V ₂ O ₅ having PTC characteristics, and a synthetic resin or glass It is formed by.

[0011]

[0012]

According to the present invention, since the heating resistor layer contains a component having PTC characteristics, the resistance value increases as the temperature rises, so that excessive temperature rise can be prevented. Also, even if the temperature rises excessively, since the protective layer is provided on the heating resistor layer,
Fire can be prevented.

[0013]

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a fixing heat roller according to an embodiment of the present invention.

FIG. 1 is a side view, and FIG. 2 is an enlarged partial sectional view. The fixing heat roller of the present invention includes a heating resistor layer 3 on an outer peripheral surface of a metal pipe 5 with an insulating layer 4 interposed therebetween, and further forms a protective layer 8 so as to cover the outer periphery of the heating resistor layer 3. A release layer 6 is provided on the outermost surface, and electrode rings 1 are attached to both ends of the heating resistor layer 3, respectively. Then, if the power supply brush 7 is brought into contact with the electrode ring 1 and is rotated between the two electrode rings 1 and 1 while energizing from the power supply 9, the heating resistor layer 3 generates heat and acts as a fixing heat roller. it can.

In the present invention, as described above, the heating resistor layer 3
Is provided so as to cover the heating resistor layer 3, even if an overcurrent flows through the heating resistor layer 3 and the temperature rises excessively, ignition can be prevented. The protective layer 8 is obtained by using a synthetic resin or glass having a heat resistance of 300 ° C. or more, specifically, by coating and baking a tyrano resin, a BT (bismaleide triazine) resin, a polyimide resin, silica, or the like. . The thickness t is set to 20 to 300 μm. This is because if the thickness t is less than 20 μm, the effect of preventing ignition or the like is poor, and if the thickness t exceeds 300 μm, the temperature rise characteristics deteriorate.

Further, the heating resistor layer 3 is composed of three components: a conductive agent, a component having PTC characteristics, and a synthetic resin or glass forming a matrix. As described above, since the heating resistor layer 3 contains the component having the PTC characteristic, the resistance value increases at a high temperature, so that the heating resistor layer 3 can have a self-control action for preventing an overcurrent.

The present invention is characterized in that the heating resistor layer 3 is constituted by the above three components. However, the conductive agent is necessary for generating an appropriate resistance value and generates heat. If it is, the resistance value will be too large,
On the other hand, if it exceeds 70% by weight, the film-forming strength is lowered and the temperature coefficient of resistance is also lowered, so the range is 10 to 70% by weight, preferably 30 to 70% by weight. A component having PTC characteristics is necessary to increase the temperature coefficient of resistance of the heating resistor layer 3. When the content is less than 1% by weight, the effect of increasing the temperature coefficient of resistance is poor. In order to impair the characteristics of the heating element, a range of 1 to 40% by weight
Preferably, it is in the range of 5 to 30% by weight. Further, the synthetic resin or glass forming the matrix is necessary for improving the film forming strength. If the amount is less than 10% by weight, the film forming strength is lowered and the temperature coefficient of resistance is lowered. Since the resistance value becomes too large, the content is set in the range of 10 to 90% by weight.

Further, the glass forming the matrix may be either crystallized glass or non-crystallized glass, but by using crystallized glass, the heating resistor layer 3 whose resistance value does not change much by heating and cooling cycles. It can be. The composition preferably contains PbO in an amount of 50% by weight or more, and preferably has a softening point of 500 ° C.
The following low melting points are preferred.

Further, as the conductive agent, Ag, Ni, A
metal material such as u, Pd, Mo, Mn, W, or Re ₂
At least one of metal compounds such as O ₃ , Mn ₂ O ₃ , LaMnO ₃ is used. Further, as a component having PTC characteristics, a metal material such as Al or Pb or a metal oxide such as V ₂ O ₅ is used.

The thickness of the heating resistor layer 3 is 5 to 100.
μm. This is because when the thickness is less than 5 μm, the resistance value is increased and the variation is liable to occur.
It is because if it exceeds, it will be easy to peel off.

In the fixing heat roller of the present invention, the electrode ring 1 has a difference in thermal expansion coefficient with the metal pipe 5 within 10 × 10 ⁻⁶ / ° C. and an electric resistivity of 10 μΩ ·
cm or less and a melting point of 800 ° C. or more, specifically, brass, copper, copper alloy, stainless steel, or the like, or a metal surface plated with nickel or the like.

By forming a chamfer such as a C-plane at the inner peripheral edge of the electrode ring 1, the bonding strength of the conductive paste can be increased. Further, the width of the electrode ring 1 is set to 4 mm or more in order to make the width larger than the width of the power supply brush 7, and preferably about 7 mm. The thickness of the electrode ring 1 is preferably 0.7 mm or more in terms of processing. Further, by forming the electrode ring 1 so as to protrude from the outer surface of the release layer 6, it is possible to prevent toner powder and paper powder from adhering to the electrode ring 1, and the protruding height is reduced. , 0.1 to 5 mm. Also, by forming a groove around the electrode ring 1,
Accumulation of toner powder and paper powder at the step can be prevented. This groove may be formed around the electrode ring 1 in the axial direction so as to communicate inside and outside the step.

Further, the metal pipe 5 has a heat conductivity of 0.1.
It is made of a metal of at least 03 cal / ° C. · cm · sec. Specifically, aluminum, an aluminum alloy, stainless steel, or the like is used, and its thickness is 0.5 to 1 mm.
The insulating layer 4 is made of polyimide, phenol, silicon,
Made of organic resin with excellent heat resistance such as borosiloxane,
The thickness varies depending on the dielectric strength. For example, in the case of polyimide, a thickness of 10 to 200 μm is preferable. The release layer 6 is made of fluororesin, silicon, or the like having excellent releasability from the toner.

Next, a method of manufacturing the heat roller of the present invention shown in FIGS.

First, the metal pipe 5 is processed into a predetermined shape.
An insulating layer 4 made of an organic resin is applied to the surface by spin coating, spray coating, dipping, or the like.
Bake in air at 50 ° C. or in a nitrogen atmosphere. On this surface, a mixture of the three components as described above mixed with an organic solvent, a binder, a dispersant, and the like to form a paste is applied by screen printing, dipping, spray coating, or the like, and baked at 400 to 500 ° C. And the heating resistor layer 3.

Thereafter, a protective layer 8 is formed on the surface of the heating resistor layer 3.
May be applied and baked, and the electrode rings 1 may be joined to both ends, and the release layer 6 may be coated.

Next, another embodiment of the present invention will be described.

The heater for hot water shown in FIG.
5 is provided with a heating resistor layer 13 via an insulating layer 14, a protective layer 18 is formed so as to cover the outer periphery of the heating resistor layer 13, and both ends of the heating resistor layer 13 Each is configured by attaching an electrode ring 11. When a current is supplied from a power source (not shown) between the two electrode rings 11, the heating resistor layer 13 generates heat and the metal pipe 15
If water is allowed to pass through it, it can be heated to make hot water.

In this hot water heater, the heating resistor layer 13
Is provided so as to cover the heating resistor layer 1.
Even if an excessive current flows through 3 and the temperature rises excessively, ignition or the like can be prevented. This protective layer 18 has a heat resistance of 300
It is obtained by coating and baking a synthetic resin or glass or the like at a temperature of at least ℃, such as a Tyranno resin, a BT (bismaleide triazine) resin, a polyimide resin, or silica, and has a thickness of 20 to 300 μm.

Further, the heating resistor layer 13 is
A material composed of 70% by weight of a conductive agent, 1 to 40% by weight of a component having PTC characteristics, and 10 to 90% by weight of a synthetic resin or glass forming a matrix is used.
As described above, since the heating resistor layer 13 contains a component having PTC characteristics, the resistance value increases at a high temperature,
It can have a self-control action to prevent overcurrent.

Next, another embodiment of the present invention will be described.

In the fixing heat roller shown in FIG. 4, the resistance value detecting means 31 is connected between the power supply brush 7 and the metal pipe 5, and the resistance value between the heating resistor layer 3 and the metal pipe 5, ie, the resistance value of the insulating layer 4, The resistance value is detected. Further, the resistance value detecting means 32 is connected between the two power supply brushes 7 to detect the resistance value of the heating resistor layer 3. Further, an electric noise detecting means 33 such as an oscilloscope or a spectrum analyzer is connected in series with the power supply 9 in the power supply line,
Electric noise in the power supply line can be detected. Although not shown, there is provided a means for cutting off the power supply from the power supply 9 when the value obtained by each detecting means becomes equal to or more than the set value or equal to or less than the set value.

The insulating layer 4 usually has a high insulation resistance, but if the insulating property is reduced during long-term use, electric leakage or fire may occur. Therefore, when the resistance value detecting means 31 detects that the resistance value of the insulating layer 4 becomes equal to or less than a predetermined value, the power supply 9 is cut off to prevent the occurrence of electric leakage or fire.

When the heating resistor layer 3 is deteriorated, the resistance becomes partially high. However, when the resistance value detecting means 32 detects that the resistance value of the heating resistor layer 3 exceeds a certain value, the power supply 9 turns on. , The occurrence of abnormal heat generation or the like can be prevented.

Further, when the heating resistor layer 3 is deteriorated and breaks, electric noise is generated.
3, when an electrical noise of an arbitrary dB or more is detected,
Electrical leakage from the power supply 9 can be prevented to prevent electric leakage and fire.

It should be noted that any one or more of the resistance value detecting means 31, 32 and the electric noise detecting means 33 may be provided. Further, it is not necessary for each detecting means to always perform the detection, and it is sufficient that the detection is performed at regular time intervals.

Experimental Example 1 As an example of the present invention, a heat roller shown in FIGS. The metal pipe 5 is made of an aluminum alloy, has a wall thickness of 0.7 mm, an outer diameter of 18 mm, and a length of 260 mm.
It was formed so as to have a thickness of about 50 μm and a dielectric breakdown voltage of 1.5 kV or more, and the heating resistor layer 3 was formed by baking the surface. The composition of the heating resistor layer 3 is such that A
A material composed of 20% by weight of g-Pd, a metal material shown in Table 1 as a component having PTC characteristics, and a balance composed of lead glass forming a matrix was used. 150 to 350, respectively
The temperature coefficient of resistance was measured in the range of ° C., and was compared with those not containing a component having PTC characteristics.

As shown in Table 1, the results were 1 for Al-based metal.
It can be seen that the temperature coefficient of resistance can be increased by using an addition amount of up to 30% by weight and 5-10% by weight for Pb-based metals. Therefore, when the heating resistor layer 3 in this range is used, the resistance value is greatly increased at a high temperature, and an overcurrent can be prevented.

[0040]

[Table 1]

Experimental Example 2 Next, in the same manner as described above, the components of the heating resistor
Pb was used as a component having the C characteristic, 10% by weight, a metal material shown in Table 2 as a conductive agent, and the balance consisting of lead glass forming a matrix were used. 150 to 3 respectively
The temperature coefficient of resistance was measured in the range of 50 ° C., and was compared with that containing no conductive agent.

The results are as shown in Table 2, 30 to 70% by weight.
It can be seen that those containing the conductive agent of (1) can increase the temperature coefficient of resistance. Therefore, the heating resistor layer 3 in this range
Is used, the resistance value greatly increases at high temperatures, and overcurrent can be prevented.

[0043]

[Table 2]

Experimental Example 3 Next, an experiment on the protective layer 8 was performed. As shown in FIG. 4, a heating resistor layer 23 made of glass, Ag and Pb is formed on a ceramic substrate 24, electrodes 21 are provided at both ends thereof, and the heating resistor layer 23 is covered with the heating resistor layer 23. The protective layer 28 was formed of various materials shown in FIG.

A voltage of AC 320 V (10 kW) was applied to each of them, and the temperature rise time up to 300 ° C. was measured with a radiation thermometer. The sample was evaluated as ○, and the sample longer than 1 second was evaluated as ×.

Further, the paper is pressed onto the protective layer 28 during energization to cause the heating resistor layer 23 to abnormally generate heat due to overvoltage, and the ratio of the burned area to the area of the heating resistor layer 23 becomes 50%.
%, Less than 100% and less than 100%, and 100%.

As shown in Table 3, the results were as follows.
Those formed with a thickness of ~ 200 µm have a burntness of 50%
And the temperature rise characteristics were less than 1 second as compared with those without the protective layer, and all were excellent results.

[0048]

[Table 3]

[0049]

[0050]

As described above, according to the present invention, in a cylindrical heater or a fixing heat roller having a heating resistor layer provided on the surface of a metal pipe with an insulating layer interposed therebetween, the heating resistor layer comprises: Ag, Ni, Au, Pd, Mo, Mn,
A mixture of a conductive agent composed of at least one of W, Re ₂ O ₃ , Mn ₂ O ₃ , and LaMnO ₃ , a component composed of at least one of Al, Pb, and V ₂ O ₅ having PTC characteristics, and a synthetic resin or glass Since the resistance temperature coefficient of the heat-generating resistor layer can be increased by the formation, the resistance value increases as the temperature rises, and excessive temperature rise can be prevented.

[0051]

Therefore, according to the present invention, it is possible to prevent accidents such as electric leakage and fire due to excessive temperature rise and deterioration of the heating resistor layer,
A highly safe cylindrical heater or fixing heat roller can be provided.

[Brief description of the drawings]

FIG. 1 is a side view showing a fixing heat roller according to an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of the fixing heat roller of FIG.

FIG. 3 is a view showing a heater for hot water according to another embodiment of the present invention.

FIG. 4 is a schematic view showing another embodiment of the fixing heat roller of the present invention.

FIG. 5 is a schematic view of an experimental device for confirming the effect of the protective layer in the present invention.

[Explanation of symbols]

 1: Electrode ring 3: Heating resistor layer 4: Insulating layer 5: Metal pipe 6: Release layer 7: Power supply brush 8: Protective layer 31: Resistance detecting means 32: Resistance detecting means 33: Electric noise detecting means

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-59-155887 (JP, A) JP-A-55-164859 (JP, A) JP-A-6-332331 (JP, A) JP-A-4- 159587 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/20 H05B 3/00

Claims (2)

(57) [Claims] 1. A heater comprising a heat generating resistor layer provided on a surface of a metal pipe via an insulating layer, wherein the heat generating resistor layer is made of Ag, Ni, Au, Pd, Mo, Mn, W, Re. _Two
O _3, Mn ₂ O _3, and <br/> conductive agent comprising at least one of LaMnO _3, Al, Pb, it at least one of V ₂ O ₅
Cylindrical heater, characterized by comprising a mixture of components, a synthetic resin or glass having that PTC characteristics. 2. A fixing heat roller having a heat generating resistor layer on a surface of a metal pipe via an insulating layer, and having a release layer on the heat generating resistor layer, wherein the heat generating resistor layer is made of Ag. ,
Ni, Au, Pd, Mo, Mn, W, Re ₂ O ₃ , Mn ₂
A conductive agent comprising at least one of O ₃ and LaMnO ₃ ;
Al, Pb, V ₂ O and component having a PTC characteristic of at least one _5, fixing heat roller characterized by comprising a mixture of a synthetic resin or glass.